Typically, mobile communication devices are electronic devices that can exchange, via wireless communication, voice and video information with a counterpart.
Through the distribution of the mobile communication devices, users can exchange information regardless of location.
The size of the mobile communication devices is also decreasing, so that the users can carry them more easily.
Recently, functions of the mobile communication device are not limited to the exchange of voice and video information, but also include other functions, such as user convenient function and entertainment function, which are newly added.
A user can enjoy various functions, such as watching a movie, listening to music, and communicating with a counterpart, using one mobile communication device. The user can also receive information using a receiver, and perform a voice communication if necessary. Thus, the time that a user carries and uses the mobile communication device is gradually increasing.
Among these functions, the function of receiving a frequency modulation (FM) radio broadcast is carried out by a receiver circuit of an FM radio receiver, which is mounted inside the mobile communication device.
The FM radio receiver circuit is highly integrated to such a degree that it can be realized with a single chip and some passive devices.
An antenna is required to be long enough to raise reception efficiency. This, however, makes it difficult to dispose the antenna inside the mobile communication device.
Conventionally, in order to overcome such a problem, the antenna having a required length is stacked on a portion of an internal board of the mobile communication device, or is disposed inside an earphone line or a speaker line, which is separately provided. Otherwise, an active antenna is used.
However, an antenna with a size of 1 mm or more cannot be disposed on the board of the mobile communication device, which is gradually reducing in size.
In the case where the earphone line or the speaker line is used, FM reception efficiency becomes terribly poor when the earphone or speaker line is detached from the mobile communication device.
While the active antenna can reduce the length of the antenna to a predetermined value, a separate electronic circuit having an active rod transistor is required to be disposed on the board, thereby increasing the manufacturing cost of the mobile communication device.